The Northern Central Railway (NCR) was the only rail that ran across Pennsylvania in a north-south direction. In southeastern Pennsylvania and northern Maryland, the now abandoned NCR has been transformed into a 44-mile long recreational corridor. Over 250,000 visitors use this trail annually. The York County, Pennsylvania Heritage Rail Trail County Park (YCHRTCP) and the NCR Trail in Gunpowder Falls State Park, Maryland provide a unique look at the regional geology. Stretching from York, Pennsylvania southward to Ashland, Maryland, the corridor lies entirely in the Piedmont containing sedimentary, igneous and metamorphic rocks ranging in age from the Proterozoic to Jurassic. Eleven different formations are encountered with the metamorphic grade increasing to the south. The trail is geologically well situated crossing the trend of the regional geology. Trail users are able to revisit the geologic settings ranging from Grenvillian crust, Laurentia continental slope and ocean bottom, divergent boundary basalts to Pangaea-rifting diabase. The geologic structure is complicated as the area has been involved in three orogenies and the Pangaean breakup. Grenvillian domes and several Taconic and Alleghanian thrust sheets and numerous folds have been mapped along the corridor. Historically, the NCR was used to carry iron ore from York County to the Ashland Furnace in Maryland.

Current development of the five-mile northern extension of the YCHRTCP will provide additional geologic history to the trail. Future development of a 12-mile York-Hanover Trolley Line and the 13-mile Hanover Branch Railroad will allow trail users to study carbonate geology and the local iron mining history respectively.